Jet fuel



JET FUEL Sol Sltolnil; and Howard W. Kruse, Inyokern, Califi, as-

signors is the United States of America as represented by the fiecretaryof the Navy No Drawing. Application November 19, 1948', Serial No.61,141

1 Claim. (Cl. 52.5)

(Granted under Title 35, U. S. Code (1952), see. 266) This inventionrelates to fuels, and more particularly to fuels for jet motors.

A common fuel currently used in jet motors is aniline. Its use has twooutstanding disadvantages. In the first place the freezing point ofaniline is 6.2 degrees centigrade. Temperatures are often encountered athigh altitudes or in arctic regions, where it is diflicult if notimpossible to employ aniline as fuel, because it solidifies and does notflow. In the second place, the ignition delay of pure aniline is undulylong compared to the total burning time of the fuel. For example, whennitrogen tetroxide is used as an oxidizer, the ignition delay of pureaniline is in the order of 350 milliseconds. This is excessive in thelight of the total burning time of around 8 seconds.

It is an object of this invention to provide improved jet motor fuelshaving low freezing points.

It is another object of this invention to provide jet motor fuels havingshort ignition delays.

It is a further object of this invention to provide improved fuelshaving higher specific impulses than prior fuels.

The freezing point of aniline has been lowered in the past by theaddition of large quantities of N-alkyl anilines and/or furfurylalcohol. Such mixtures contain large quantities of low energy additives,and in addition have long ignition delays. In the case of the furfurylalcohol additives, the fuel becomes unstable during storage.

In accordance with the instant invention, the characteristics of anilineas a fuel are markedly improved by the addition of hydrazine. It hasbeen found that hydrazine and aniline form a eutectic mixture when about18% by weight hydrazine is dissolved in about 82% by weight aniline.This mixture freezes at approximately -39 centigrade.

More broadly expressed, a low freezing point fuel, and hence a fuel ofdefinite advantage in jet motors, may be formed by dissolving hydrazineeither in aniline or in one of the aliphatic derivatives of aniline, orin a mixture of aniline and/ or several of the aliphatic derivativesthereof. In such cases there is a eutectic proportion for which thefreezing point is lower than for either pure hydrazine or pure anilinederivative.

Furthermore, the added hydrazine also serves to increase the specificimpulse of the aniline, or aniline derivative, fuel; and also lowers theignition delay of the fuel.

While all of the aliphatic derivatives of aniline, as well as anilineitself, or any combinations of these compounds, are benefited by theaddition of hydrazine, it is preferred, after aniline itself, to employin the mixture one or more of the N-substituted aliphatic derivatives ofaniline, i. e., one or more of the group represented by:

RR'NCsHs 2,712,496 Fatented- July 5,. 1.955

Where R is one of the class consisting'of (1) An aliphatic radical (2)Hydrogen atom R is one of the class consisting of- (1), An aliphaticradical (2) Hydrogen atom CsH5 is a benzene radical Of the abovecompounds, aniline is the preferred basic fuel, the next preferencebeing a fuel comprised of hydrazine dissolved in di methyl aniline. Ineither case, it; ispreferred to employ a eutectic mixture of: hydrazinein, the particular aniline compound used:

The striking advantage of using hydrazine to lower the freezing pointmay be seen in the following table, wherein aniline itself is used asthe other compound in the mixture:

The effect upon ignition delay of dissolving hydrazine in aniline fuelis shown in the following table:

TABLE II Ignition Delay of Aniline-hydrazine, with Nitrogen Tetroxide asOxidizer Percentage by Weight Ignition Delay, Milli- Hydrazine Anilineseconds Fuels composed of hydrazine dissolved in aniline and/ oraliphatic derivatives of aniline have been found to have the advantagesof: lowered melting point, including formation of eutectic mixtures;lowered ignition delay; and higher specific impulse, than the same fuelswithout the hydrazine.

Specific examples of fuels which are improved in this manner by theaddition of hydrazine and which are encompassed in the above generaldescription are:

aniline methyl-aniline ethyl-aniline diethyl-aniline propyl-anilineisopropyl-aniline methyl-ethyl-aniline Obviously many modifications andvariations of the present invention are possible in the light of theabove teachings. It is therefore to be understood that within the scopeof the appended claim the invention may be practiced otherwise than asspecifically described.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

What is claimed is:

A fuel comprising approximately 82% aniline by weight and 18% hydrazineby weight.

King June 21, 1949 Solomon Sept. 5, 1950 4 OTHER REFERENCES Zucrow,Liquid Fropellant Rocket Power Plants, Journal of the American RocketSociety, No. 72, pages 26-44, December 1947. (Copy in Div. 43.).

Klein, Fuels for Jets, 8., A. B. Journal, pages 22-28, December 1947.(Copy in Patent Ofiice Library.)

Liebhafsky, Chimie and Industrie, vol 56, No. 1, page 1.9, July 1946.(Copy in Bureau of Standards Library.)

Science News Letter, page 25, July 10, 1948. (Copy in Patent OfficeLibrary.)

Deming, General Chemistry, 3rd edition John Wiley & Sons, Inc., New York(1930), pages 155, 156. (Copy in Scientific Library.))

